1. Field of the Invention
This invention relates to a floater-type heat treating furnace, especially floatation-type pressure pads which are designed to float a continuous strip of material, e.g. aluminum, copper or steel, on a fluidized bed as the strip moves through the furnace. The pressure pad can be located both over and underneath the strip.
2. Description of the Prior Art
Pressure pads are widely used to float metal strips of easily deformed materials through a heat treating furnace because such strips can be damaged if they contact rigid rolls which normally support and move metal strips through the furnace.
Generally, as shown in FIG. 7, each pad 40 comprises a plenum chamber 41. The plenum chamber 41 comprises two parallel rows or lines of jet nozzles 42,42' which extend one edge to the another edge of a strip and are perpendicular to the movement of the strip S. They are designed to direct streams or jet of fluid such as gas from a plenum chamber 41 to float the strip S. Each row of jet nozzles 42,42' may consist of a continuous slit or slot which is coextensive with the width of the strip S. These nozzles 42,42' are designed to create static pressure by blowing gas against the strip.
With prior pressure pads 40, previous to this invention, large amount of fluid moves toward edges of the strip S and then escapes from the area underneath the strip S easily. By not containing the fluid properly, area B of the effective static pressure underneath the strip S tends to be small. Consequently, it has been difficult to float strips steadily and results in fluttering or scratching, especially when hot fluid is used because of low density of hot fluid gas. Therefore, it has taken large amount of fluid to float strips.